Derrick centering apparatus



Jan. 1, 1963 Filed April 29, 1958 E. A. BENDER DERRICK CENTERINGAPPARATUS 3 Sheets-Sheet l /d x g l 2% w I INVENTOR I 425 ZzzZ4.ZendeATTORNEYS Jan. 1, 1963 E. A. BENDER 3,071,213

DERRICK CENTERING APPARATUS Filed April 29, 1958 3 Sheets-Sheet 2ATTORNEY;

Jan. 1, 1963 E. A. BENDER DERRICK CENTERING APPARATUS 5 Sheets-Sheet 5Filed April 29, 1958 ZZZ INV EN TOR JZhiZAJe Maw ATTORNEYS.

ilnited rates Patent @hfice 3,h'il,2l3 Patented Jan. 1, 1%63 3,071,213DERRECK CENTERHNG APPARATUS Emil A. Bender, R0. Box 52, Bakersfield,Calif. Filed Apr. 29, W58, Ser. No. 731,748 10 Claims. (Cl. 18-l5) Thepresent invention relates generally to the well-drilling art and is moreparticularly directed to certain new and useful improvements in oil welldrilling derricks.

In the well-drilling art, and particularly in the drilling of oil wellswhich require the utilization of extremely heavy, massive equipment, itis highly important that the drilling derrick, when erected, occupy asubstantially vertical position in order to align the traveling blockwith the center line of the hole to avoid rubbing the side of the rotarytable. Furthermore, during the actual drilling operation far greaterloads are imposed on the derrick structure and it is thus extremelyimportant that the effective center line of the derrick be positioned asaccurately as possible with respect to the center line of the well.

As is well known to those skilled in the art, in the erection ofderricks in the past it has been the practice to employ heavy jacks orother lifting devices for the purpose of raising the individual derricklegs so that suitable shims could be inserted or removed to adjust therelative heights of the individual derrick legs and thereby theeffective center line of the derrick itself. The use of such equipmentin accordance with prior practices is not only difficult, time consumingand dangerous but, in addition, still leaves something to be desiredfrom the standpoint of accuracy in view of the inherent cut and trynature of the process. Of possibly even greater importance is the factthat adjustment of the derrick center line may become necessary whiledrilling operations are in progress and the use of jacks and shims atsuch time is practically out of the question whereas shutting downoperations for a length of time sufiicient to permit the utilization ofjacks and shims may be highly detrimental especially during criticalphases of the drilling operation.

In the light of the foregoing, it is a principal object of the presentinvention to provide novel structure by means of which the individuallegs of a well-drilling derrick may be individually adjusted in suchmanner as to accurately locate the effective center line of the derrickand its traveling block with respect to the center line of the well.

An important object of the invention is to provide apparatus of the typedescribed which avoids the inherent difficulties and dangers of knownmethods of adjusting the center line of a derrick and which provides forexpeditious and easy adjustment not only during erection of the derrickbut also at any time during the drilling operations.

Another object of the invention is to provide apparatus of the typedescribed in which the adjustment of the individual derrick legs withrespect to the sub-base or supporting base structure is effected throughthe use of eccentric pin mountings or eccentric hinges permittingrelatively fine adjustments to be made.

A further object of the invention is to provide an eccentric hingemounting for a derrick of the type described including limit stops soarranged as to prevent over center travel of the eccentric portion ofthe device while at the same time insuring proper original assembly ofthe eccentric hinge.

An additional object of the invention is to provide an eccentric hingeof the type described including means for positively locking theeccentric hinge pin in various adjusted positions.

Yet another object of the invention is to provide an eccentric hinge ofthe type described in which the locking means comprises a locking gearincluding a plurality of teeth each having both a radial face and aninclined face so that the loads on the derrick regs may be transmittedto the supporting base structure through the inclined flat teeth of thelocking gear thereby avoiding any load component tending to unlock themechanism.

A still further object of the invention is to provide apparatus of thetype described wherein the eccentric hinge includes a bearing surfacecurved in more than one plane to permit limited universal pivotingmovement.

Another object of the invention is to provide structure of the typedescribed which is both simple and rugged and which may be inexpensivelyfabricated and require a minimum of maintenance attention in use.

The foregoing together with other and further objects and advantages ofthe invention will become more readily apparent to those skilled in theart from a consideration of the following detailed specification takenin conjunction with the accompanying figures of drawing in which:

FIGURE 1 is a fragmentary side elevational view, largely schematic, ofone form of the derrick illustrating the location of preferredembodiments of eccentric hinge fittings in accordance with the presentinvention;

FIGURE 2 is a fragmentary end view looking from the right in FIGURE 1 inwhich parts of the structure are broken away to further illustrate thelocation of the improved eccentric hinge fittings in accordance with thepresent invention;

FIGURE 3 is a side elevational view of one of the upper eccentric hingefittings of FIGURES 1 and 2 shown to a somewhat larger scale but greatlyreduced from actual size;

FIGURE 4 is a horizontal transverse cross-sectional view through one ofthe upper or main eccentric hinge fittings taken substantially along theline d4 of FIG- URE 3;

FIGURE 5 is a vertical transverse cross-sectional View illustrating adetail of the locking bar and guide slot and is taken substantiallyalong the line 5-5 of FIGURE 3;

FIGURE 6 is a fragmentary detailed view of one of the main derrick legbearings apart from the sub-base structure and with portions of the legbearing structure broken away to illustrate the interior construction;

FIGURE 7 is a vertical transverse cross-sectional view through the mainderrick leg bearing taken substantially along the line '77 of FIGURE 6;

FIGURE 8 is a side elevational view similar to FIG- URE 3 butillustrating one of the lower eccentric hinge fittings as shown inFIGURES 1 and 2; and

FIGURE 9 is a transverse cross-sectional. view through one of the lowereccentric hinge fittings taken substan tially along the line 9-9 ofFIGURE 8.

Referring now in somewhat greater detail to the indi vidual figures ofthe drawing and in particular to FIG- URES l and 2 thereof, eccentrichinges in accordance with the present invention are illustrated in thepositions which they would occupy in the well-known type of oil drillingderrick. The complete derrick structure comprises a base or sub-basedesignated generally by reference numeral 10 provided with a pair ofpedestal like structures 12 at its opposite sides to which are pivotallyconnected the legs 14- of the main derrick body designated generally byreference numeral 16. The structural details of the sub-base it? andmain derrick body 16 are not particularly significant so far as thepresent invention is concerned and it will be understood that suitablebraces and girts 18 and 2%) may be provided in the derrick body whilevertical posts 22 and diagonal braces 24 serve to interconnect the upperand lower frames 26 and 28 at opposite sides of the Sub-base 10. Theparticular derrick selected for the purpose of illustration in thepresent case also comprises a pair of lifting legs 30 pivotallyconnected at their lOWer ends to the sub-base lift and provided withrollers or the like 32 at their upper ends which are slidable alongtracks provided on the front legs 34 of the derrick body. Derricks ofthis type are generally referred to as embodying the lever liftprinciple, the lifting legs 30 being connected by suitable cables 36 andsheaves 38 to the usual traveling block of the derrick (not shown) sothat, through operation of the draw works the lifting legs 30 areactuated so that the rollers 32 slide along the front derrick legs 34 toraise the derrick body into operating position at which time the liftinglegs 30 are positively locked in any suitable manner as by means oflatches designated generally by reference character 41), the liftinglegs 39 then becoming integral parts of the derrick while the latter isin operating position.

As indicated above, the principles of the present invention are notlimited in their applicability solely to derricks of the type disclosedin FIGURES 1 and 2 of the drawings but may be employed in substantiallyany known type of derrick construction. However, the derrick illustratedin FIGURES 1 and 2 has been selected for the purpose of explaining theinvention since it embodies hinges having useful functions entirelyapart from the features of the present invention and, in addition,employs hinges which preferably permit a limited amount of universalpivoting action. Specifically, therefore, as shown in FIGURES 1 and 2,eccentric hinge structures in accordance with the present invention aredesignated generally by reference numerals 42 and 44, the hinges 42, orupper hinges, serving to pivotally connect the main derrick body 16 tothe sub-base 16 and the lower hinges 44 serving to pivotally connect thelifting legs 30 to the sub-base 10. As will hereinafter become moreapparent, the specific structure of the hinge structures 42 and 44differs slightly, the upper hinges 42 being illustrated in somewhatgreater detail in FIGURES 3 and 4 of the drawings and the lower hinges44 being similarly illustrated in greater detail in FIGURES 8 and 9thereof.

Referring now particularly to FIGURES 6 and 7 of the drawings, there isillustrated in somewhat greater detial the construction of the bearingmeans which is provided at the lower end of the main derrick body. Asshown in these views, the lower end of the rear derrick leg 14 is weldedor otherwise rigidly secured to a flanged cap piece 46 which in turn issimilarly secured to a converging extension 48 of the front derrick leg34. Transversely of the hinge 42, the cap piece 46 is provided with apair of depending plates 50-52 which are both spaced laterally of thehinge and also notched as indicated at 54 for a reason to be hereinafterdescribed. Between the plates 50-52, there is provided a solid block 56which is preferably welded or otherwise secured in any convenient mannerto the plates ll52 and also to the cap piece 46. A generally U-shapedmember 58 also fits between the plates 5tl'52 and is removably securedto the block 56 in any suitable manner as by means of a bolt 60 and nut62. The U-shaped member 53 is preferably also shaped in its centralportion as indicated by reference numeral 64 in such manner as toprovide a bearing surface within which is journaled to stub shaftdesignated generally by reference numeral 6! which will be hereinaftermore fully described. It is to be understood that the specific detailsof the construction of the bearing means just described are primarilyintended to simplify and expedite the initial assembly of the upperhinges 42 prior to raising the main derrick body 16 and the improvedeccentric hinge fittings in accordance with the present invention arenot to be construed as limited to this specific type of bearingconstruction.

Referring now particularly to FIGURES 3 and 4 of the drawings, thebearing means which has just been described is illustrated in theposition which it occupies when assembled with the mating structureprovided on the sub-base it). As shown in these views, the pedestal 12mounted above the sub-base 16 includes a vertical member 68 having a cappiece 76 welded or otherwise rigidly attached to its top end and mayalso include suitable gussets or bracing structures 72. Mounted on topof the cap piece 76 in any convenient manner as by welding or the like,is a bearing structure in the form of a clevis comprising transverselyspaced plates 74 and 76. Each of the plates 7476 is apertured to provideconcentric bearings 78 and 34 in which are journaled the concentric endportions 82 and 84 of the stub shaft 66. The stub shaft 66 is alsoprovided with an eccentric portion 86 which lies between the concentricend portions and the eccentric portion 86 is journaled in the bearing 64provided at the end of the main derrick body. The stub shaft 66 is alsoprovided with a squared end portion as projecting outward to lieexteriorly of the clevis, by means of which a suitable tool (not shown)may be employed for the purpose of rotating the stub shaft 66. The stubshaft 66 may be held in place within the clevis in any convenient manneras by means of a locking pin 90.

From the description thus far, it will be apparent that rotation of thestub shaft 66 by means of a wrench or other suitable tool in engagementwith the squared portion 88 will cause a relative displacement of thebearings in which are journaled the concentric shaft portions 82 84 andthe eccentric shaft portion 86 lying therebetween. In order that thestub shaft 86 may be positively retained in various adjusted positionsof rotation, a shallow tubular housing $2 is welded or otherwisesuitably secured to the outer face of one of the clevis Walls, in thisinstance the outer wall of the plate 74, and it Will be noted that thehousing 92 surrounds a projecting end 32 of the stub shaft 66. A lockinggear 94 is securely attached to the projecting end 82 of the stub shaft66 in any suitable manner as by welding or the like and also lies withinthe housing 92 being spaced from the outer face of the plate 74 by meansof suitable stops or other abutments 96 which are connected to thelocking gear 94 but are free to slide over the outer surface of theplate 74. It will thus be understood that the locking gear 94 and stops96 rotate with the stub shaft 66 within the housing 2 whenever the stubshaft is rotated by engagement of a wrench or suitable tool with thesquared portion 88.

Still referring to FIGURES 3 and 4, it will be noted that the interiorof the housing 9'2 is provided with a partial ring shaped stop 93secured to the housing as by welding or the like and an abutment 16% issimilarly secured to the outer face of the locking gear 94 in suchmanner that, as the locking gear 94 rotates with the stub shaft 66, theabutment will rotate in the plane containing the stop 98. It is to beparticularly noted, as shown in FIGURE 3, that the locking gear 94 isprovided with teeth only over a portion of its periphery, the remainderof the periphery of the locking gear 94 being smooth and of a radiusslightly less than the radius of the ring shaped stop 98. However, thetoothed portion of the locking gear 94 has a radius somewhat greaterthan the radius of the stop 98 so that, when the stub shaft 66 andattached locking gear 94 are being a sembled into the positions shown inFIGURES 3 and 4, the angular position of the stub shaft must be as shownin these views since, otherwise, the toothed portion of the locking gearwould come into engagement with the stop 98 thereby preventing completeassembly. This is a particularly important feature of the inventionsince, by reason of this construction, the entire device is renderedsubstantially foolproof in assembly and, since the stub shaft andlocking gear can only be inserted in one position to form a part of thecomplete hinge, the relative angular positions of the concentric andeccentric portions of the stub shaft 66 are such as to provide aninitial centering action so that rotation of the stub shaft 66 in eitherdirection from initial assembly position will be effective to producemaximum displacement of the hinge elements in either direction.

Referring once again to FTGURES 3 and 4- of the drawings, there isillustrated a preferred form of locking means for releasably locking thestub shaft 66 in various positions of adjustment. As illustrated inthese views, the locking device comprises an open rectangular guide slotMP2 welded or otherwise suitably secured to the outer wall of thehousing 92 and forming an extension of a suitable aperture in the latterlocated substantially opposite the center of the partial ring shapedstop 98. A locking bar 104 (FIG. 5) also of rectangular shape incross-section, is slidable within the guide slot Hi2 radially of thelocking gear 94. At its inner end, the locking bar 164 is provided withseveral teeth which are preferably of the same size as the teeth formedon a portion of the periphery of the locking gear 94 and are engageabletherewith. A suitable bolt 1% provided with a nut 108 may convenientlybe employed for the purpose of securing the locking bar in lockingengagement with the locking gear 94. It will also be noted in FIGURE 3that each of the teeth on the periphery of the locking gear 94 isprovided with both a radial and an inclined face so that when the teethon the locking bar 104 are in engagement with the teeth on the lockinggear 94, there will be no component of force transmitted from thederrick body through the eccentric hinge fitting to the locking gear 94which may tend to disengage the teeth of the locking bar 104 therefrom.In other words, by engagement of the locking bar 1424 with the lockinggear 94 along tooth faces which are truly radial, there is no componentof force tending to push the locking bar 104 out of engagement.

As mentioned above, the construction of the lower hinges 44- isillustrated in FIGURES 8 and 9 of the drawings. In general, the hinges4-4 are basically similar to the upper hinges 42 but include additionalstructure providing for limited universal pivoting movement of the mastor, more accurately, the lifting leg 36 forming a part of the mast. Asillustrated in these views, the clevis constituting the fixed portion ofthe eccentric hinge is provided by plates lid- 112 welded to a baseplate 114 formed as an extension of the beam 28 on the subbase 19. Theremaining portions of the hinge assembly, including the housing and thelocking bar, are substantially identical with the structure of the hinge42 and have been given the same reference numerals in the drawings. Itis to be noted, however, that, for ease of operation, the relativepositions of the stop 93, abutment res, and locking bar Mid, have beenshifted angularly from the substantially horizontal positionsillustrated in FIGURE 3. The operation of these elements is neverthelessexactly the same as in the case of the upper hinges 42.

The principal difference in the construction of the hinges 42 and i4 isbest shown in FIGURE 9 wherein it will be noted that the lower end 116of the lifting leg 3% is provided with an additional bearing surfacewhich is curved in more than one plane as indicated by reference numeral118. The bearing surface 113 is formed in the interior of a sleeve 129which, in turn, is held in place within the projecting end 115 of thelifting leg 3% in any suitable manner as by means of a locking ring 122.The bearing 118 journals another sleeve 124- provided with a surface 126which is also curved in more than one plane and an inner surface 128within which is journaled the eccentric portion of the stub shaft d6. Byreason of the construction just described, the lifting legs 39 arecapable of limited universal pivoting movement so that the angularposition of each of the lifting legs 3G with respect to the vertical mayvary as the main derrick body is being raised into operating position inorder to accommodate the relatively diverging tracks formed upon theequally diverging front derrick legs 34. However, once the derrick bodyhas been raised into operating position, the operation of the lowerhinges 44 for the purpose of adjusting the effective center line of thederrick with respect to the well is substantially identical to theoperation of the upper hinges 42.

While it is believed that the operation of the device will be generallyapparent from the description thus far, a brief explanation will begiven. Assuming the derrick to be fully assembled and in operatingposition relative to a well, that is, with the derrick body 16 andsub-base it} in the general positions as illustrated in FIGURES 1 and 2,it will be further assumed that the effective center line of the derrickis out of alignment with the center line of the well either as a resultof errors in locating the derrick during erection or as a result ofunusual conditions arising during a drilling operation. In order toadjust the effective center line of the derrick with respect to thewell, the operator in charge may adjust any or all of the hinges 42-44,the particular hinge or combination thereof to be adjusted being largelya matter of discretion within the judgment and experience of the:operator in charge. It will be understood that due to the fact that thederrick is relatively high as compared to its relatively narrow base,even a slight adjustment of any of the hinges 42- id will produce agreatly magnified displacement of the top of the derrick, whichdisplacement will be reflected directly in the position of the travelingblock which hangs from the top of the derrick.

Assuming that the misalignment of the efiective center of the derrickwith respect to the weil is of such nature that it can be corrected bysimple adjustment of one of the hinges 4,2, the operator will first havea large wrench or equivalent tool attached to the squared end 88 of thestub shaft as So that the latter may be held against accidentaldisplacement. The nut hi may then be removed from the bolt 1% and thelatter withdrawn so as to permit the locking bar iii-i to be withdrawnoutwardly through the guide slot 102 thereby causing the teeth at theinner end of the locking bar lithito become disengaged from the teeth onthe locking gear 94. After this has been done, the operator may causethe stub shaft 66 to be rotated by the tool in engagement with thesquared end 88 and, since the concentric shaft portions 82 and 84 arefixed in the bearings 7f53@ formed in the clevis provided by plates 747secured to the sub-base 1d, the eccentric stub shaft portion 36 will bedisplaced relative to the concentric portions 32-34 thereby displacingthe bearing formed in the elements 5h-52 and 5'8. As a result thederrick leg 14- and entire derrick body 16 will be caused to moveupwardly or downwardly depending upon which way the stub shaft 65 isrotated, until the desired position of adjustment of the traveling blockhas been achieved.

After the stub shaft 66 has been rotated into the desired position ofadjustment, the locking bar 1&4 is reinserted through the guide slotHi2. to cause the teeth at its inner end to engage with a difierentgroup of teeth on the periphery of the locking gear 94 and the bolt 1&6is reinserted and held in place by the nut 16 8. Since the abutment 19%rotates in a plane which also contains the stop 98, it will be apparentthat rotation of the locking gear 94 and its attached stub shaft 66 islimited by the relative positions of the parts g8 and Mid. This is a particular safety feature since, by properly arranging the size andposition of these elements, the eccentric portion of the stub shaft 66can never be rotated to an over center position such as might cause areversal of the derrick load upon the operating wrench or other tool andthus possible injury to the operators.

In practice, it is deemed preferable to arrange all of the eccentrichinges so that the eccentric portions thereof operate towards the centerof the derrick. In this way, the motions of the eccentrics will add toeach other laterally and avoid any pushing or pulling stresses on thederrick structure. While this is an important operating feature, thefundamental principle of operation is deemed to be adequately covered bythe preceding description of operation of a single eccentric hinge 42.

While there is disclosed herein a preferred embodiment of the inventionsolely for the purpose of illustration, it will be obvious that numerousmodifications, alterations and deviations will occur to those skilled inthe art Without departing from the spirit or scope of the invention asdefined by the following claims.

I claim:

1. in an oil drilling derrick, a sub-base and a main derrick body havingpairs of rear legs and front legs provided with bearings at their lowerends, a plurality of hinges pivotally connecting said legs to saidsub-base, each of said hinges comprising a clevis attached to saidsub-base and having a pair of concentric bearings formed in its ppositeWalls, a stub shaft having concentric end portions journaled in saidclevis bearings and an eccentric portion lying therebetween andjournaled in said leg bearings, means on said stub shaft exterior-1y ofsaid clevis for rotating said stub shaft, a shallow tubular housingattached to the outer face of one of said clevis Walls and surrounding aprojecting end of said stub shaft, a toothed locking gear attached tosaid stub shaft Within said housing, a partial ring shaped stop attachedto the interior of said housing, an abutment attached to the outer faceof said gear for engagement with said stop, said gear having a portionof its periphery smooth and of a radius less than that of said ringshaped stop and the teeth covering the remainder of the periphery ofsaid gear having a radius greater than that of said stop and each havinga radial face and an inclined face, means forming an open rectangularguide slot in said housing opposite said stop, a locking bar slidable insaid slot radially of said gear and having teeth at its inner endengageable with the teeth of said gear, and a bolt engageable with theWalls of said slot and said bar for holding the latter in lockingengagement with said gear.

2. In a derrick, a sub-base and a main derrick body provided withbearing means at its lower end, hinge means pivotally connecting saidderrick body to said sub-base comprising a clevis attached to saidsub-base and having a pair of concentric bearings formed in its oppositeWalls, a stub shaft having concentric end portions journaled in saidclevis bearings and an eccentric portion lying therebetween andjournaled in said bearing means, means on said stub shaft exteriorly ofsaid clevis for rotating said stub shaft, a shallow tubular housingattached to the outer face of one of said clevis Walls and surrounding aprojecting end of said stub shaft, a toothed locking gear attached tosaid stub shaft within said housing, a partial ring shaped stop attachedto the interior of said housing, an abutment attached to the outer faceof said gear for engagement with said stop, said gear having a portionof its periphery smooth and of a radius less than that of said ringshaped stop and the teeth covering the remainder of the periphery ofsaid gear having a radius greater than that of said stop and each havinga radial face and an inclined face, means forming an open rectangularguide slot in said housing opposite said stop, a locking bar slidable insaid slot radially of said gear and having teeth at its inner endengageable with the teeth of said gear, and a bolt engagea le With theWalls of said slot and said bar for holding the latter in lockingengagement with said gear.

3. In a derrick, a sub-base and a main derrick body, hinge meanspivotally connecting said derrick body to said sub-base comprisingbearing means on said sub-base and said derrick body, respectively, astub shaft having a portion journaled in said sub-base bearing means andan eccentric portion journaled in said derrick body bearing means, meanson said stub shaft for rotating said stub shaft, a housing attached tosaid sub-base bearing means and surrounding a projecting end of saidstub shaft, a toothed locking gear attached to said stub shaft Withinsaid housing, a partial ring shaped stop attached to the interior ofsaid housing, an abutment attached to the outer face of said gear forengagement with said stop, said gear having a portion of its peripherysmooth and of a radius less than that of said ring shaped stop and theteeth covering the remainder of the periphery of said gear having aradius greater than that of said stop and each having a radial face andan inclined face, means forming an open rectangular guide slot in saidhousing opposite said stop, a locking bar slidable in said slot radiallyof said gear and having teeth at its inner end engageable with the teethof said gear, and a bolt engageable With the walls of said slot and saidbar for holding the latter in locking engagement with said gear.

4. In a derrick, a sub-base and a main derrick body, hinge meanspivotally connecting said derrick body to said sub-base comprisingbearing means on said sub-base and said derrick body, respectively, astub shaf having a portion journaled in said sub-base bearing means andan eccentric portion journaled in said derrick body bearing means, meansfor rotating said stub shaft, a housing attached to said sub-basebearing means and surrounding a projecting end of said stub shaft, atoothed locking gear attached to said stub shaft Within said housing, apartial ring shaped stop attached to the interior of said housing, anabutment attached to said gear for engagement with said stop, said gearhaving a portion of its periphery smooth and of a radius less than thatof said ring shaped stop and the'teeth covering the remainder of theperiphery of said gear having a radius greater than that of said stopand each having a radial face and an inclined face, means forming aguide slot in said housing, a locking bar slidable in said slot radiallyof said gear and having teeth at its inner end eugageable w th the teethof said gear, and means for holding said bar in locking engagement withsaid gear.

5. In a derrick, a base and a mast, hinge means pivotally connectingsaid mast to said base comprising bearing means on said base and saidmast, respectively, a stub shaft having a portion journaled in said basebearing and an eccentric portion journaled in said mast bearing means,means for rotating said stub shaft, a housing on said base surrounding aprojecting end of said stub shaft, 2. locking gear attached to said stubshaft within said housing, said gear having a plurality of teeth eachprovided with a radial face and an inclined face, means forming a guideslot in said housing, a locking bar slidable in said slot radially ofsaid gear and having teeth at its inner end engageable with the teeth ofsaid gear, and means for holding said bar in locking engagement withsaid gear.

6. In a derrick, a base and a mast, hinge means pivotally connectingsaid mast to said base comprising bearing means on said base and saidmast, respectively, a stub shaft having a portion journaled in said basebearing means and an eccentric portion journaled in said mast bearingmeans, means for rotating said stub shaft, a housing on said basesurrounding a projecting end of said stub shaft, a locking gear attachedto said stub shaft Within said housing, said gear having a plurality ofteeth each provided With a radial face an an inclined face, meansforming a guide slot in said housing, and a locking bar slidable in saidslot radially of said gear and having teeth at its inner end engageablewith the teeth of said gear.

7. In a derrick, a base and a mast, hinge means pivotally connectingsaid mast to said base comprising bearing means on said base and saidmast, respectively, a stub shaft having a portion journaled in said basebearing means and an eccentric portion journaled in said mast bearingmeans, means for rotating said stub shaft, a housing on said basesurrounding a projectin end of said stub shaft, a locking gear attachedto said stub shaft Within said housing and having a plurality of teeth,means forming a guide slot in said housing, and a locking bar slidablein said slot radially of said gear and having teeth at its inner endengageable with the teeth of said gear.

8. In a derrick, a base and a mast, hinge means pivotally connectingsaid mast to said base comprising bearing means on said base and saidmast, respectively, a stub shaft having a portion journaled in said basebearing means and an eccentric portion journaled in said mast bearingmeans, means for rotating said stub shaft, a locking gear attached tosaid stub shaft and having a plurality of teeth, and a locking barslidable radially of said gear and having teeth at its inner endengageable with the teeth of said gear.

9. In a derrick, a base and a mast, hinge means pivotally connectingsaid mast to said base comprising bearing means on said base and saidmast, respectively, a stub shaft having a portion journaled in said basebearing means and an eccentric portion journaled in said mast bearingmeans, means for rotating said stub shaft to adjust the relativepositions of said mast and said base, and means for releasably lockingsaid stub shaft in various positions for adjustment, said mast bearingmeans including a first bearing surrounding the eccentric portion ofsaid stub shaft, and a second bearing concentric with said first bearingand provided with a bearing surface curved in more than one planewhereby said mast is capable of limited universal pivoting movement.

10. In a derrick, a base and a mast, hinge means pivotally connectingsaid mast to said base comprising bearing 5 means on said base and saidmast, respectively, a stub shaft having a portion journaled in said basebearing means and an eccentric portion jonrnaled in said mast bearingmeans, means for rotating said stub shaft to adjust the relativepositions of said mast and said base, and 10 means for releaseablylocking said stub shaft in various positions for adjustment, said mastbearing means including a bearing surface curved in more than one planewhereby said mast is capable of limited universal pivoting movement.

References Cited in the file of this patent UNITED STATES PATENTS

1. IN AN OIL DRILLING DERRICK, A SUB-BASE AND A MAIN DERRICK BODY HAVINGPAIRS OF REAR LEGS AND FRONT LEGS PROVIDED WITH BEARINGS AT THEIR LOWERENDS, A PLURALITY OF HINGES PIVOTALLY CONNECTING SAID LEGS TO SAIDSUB-BASE, EACH OF SAID HINGES COMPRISING A CLEVIS ATTACHED TO SAIDSUB-BASE AND HAVING A PAIR OF CONCENTRIC BEARINGS FORMED IN ITS OPPOSITEWALLS, A STUB SHAFT HAVING CONCENTRIC END PORTIONS JOURNALED IN SAIDCLEVIS BEARINGS AND AN ECCENTRIC PORTION LYING THEREBETWEEN ANDJOURNALED IN SAID LEG BEARINGS, MEANS ON SAID STUB SHAFT, A HOLLOWTUBULAR HOUSING ATTACHED TO THE OUTER FACE OF ONE OF SAID CLEVIS WALLSAND SURROUNDING A PROJECTING END OF SAID STUB SHAFT, A TOOTHED LOCKINGGEAR ATTACHED TO SAID STUB SHAFT WITHIN SAID HOUSING, A PARTIAL RINGSHAPED STOP ATTACHED TO THE INTERIOR OF SAID HOUSING, AN ABUTMENTATTACHED TO THE OUTER FACE OF SAID GEAR FOR ENGAGEMENT WITH SAID STOP,SAID GEAR HAVING A PORTION OF ITS PERIPHERY SMOOTH AND OF A RADIUS LESSTHAN THAT OF SAID RING SHAPED STOP AND THE TEETH COVERING THE REMAINDEROF THE PERIPHERY OF SAID GEAR HAVING A RADIUS GREATER THAN THAT OF SAIDSTOP AND EACH HAVING A RADIAL FACE AND AN INCLINED FACE, MEANS FORMINGAN OPEN RECTANGULAR GUIDE SLOT IN SAID HOUSING OPPOSITE SAID STOP, ALOCKING BAR SLIDABLE IN SAID SLOT RADIALLY OF SAID GEAR AND HAVING TEETHAT ITS INNER END ENGAGEABLE WITH THE TEETH OF SAID GEAR, AND A BOLTENGAGEABLE WITH THE WALLS OF SAID SLOT AND SAID BAR FOR HOLDING THELATTER IN LOCKING ENGAGEMENT WITH SAID GEAR.